Estimating the Contribution of Dynamical Ejecta in the Kilonova Associated with GW170817
Estimating the Contribution of Dynamical Ejecta in the Kilonova Associated with GW170817
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DOI：
10.3847/2041-8213/aa9478
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发表时间：
2017-12-01
影响因子：
7.9
通讯作者：
Zweizig, J.
中科院分区：
文献类型：
--
作者：
Abbott, B. P.;Abbott, R.;Zweizig, J.
引力波（GW）信号GW 170817的来源，很可能是一个双中子星星合并，也被电磁观测到，提供了这种类型的第一个多信使观测。为期两周的电磁（EM）对应物具有指示r过程引起的光学瞬变的签名，称为千诺瓦。这封信探讨如何动态喷出物的质量可以估计没有直接的电磁观测的千诺瓦，使用GW测量和校准的数值模拟合并与动态喷出物的唯象模型。具体而言，我们应用该模型的GW测量推断的二进制质量，并使用由此产生的质量的动态喷出物估计其贡献（没有风喷出物的影响），相应的kilonova光变曲线从各种模型。假设中子星是慢旋转的，对于各种状态方程，动态喷出物质量分布在M-ej = 10（-3）-10（-2）M圆点之间。此外，我们使用我们的估计的动态喷出物的质量和中子星星合并率从GW 170817推断，限制这样的事件的贡献的r-过程中的元素丰度在银河系时，喷出物质量合并后的风被忽略。我们发现，如果大于或接近10%的物质动态喷出的二元中子星星（BNS）合并被转换为r-过程元素，GW 170817一样的BNS合并可以完全占银河系中观察到的r-过程材料的量。
The source of the gravitational-wave (GW) signal GW170817, very likely a binary neutron star merger, was also observed electromagnetically, providing the first multi-messenger observations of this type. The two-week-long electromagnetic (EM) counterpart had a signature indicative of an r-process-induced optical transient known as a kilonova. This Letter examines how the mass of the dynamical ejecta can be estimated without a direct electromagnetic observation of the kilonova, using GW measurements and a phenomenological model calibrated to numerical simulations of mergers with dynamical ejecta. Specifically, we apply the model to the binary masses inferred from the GW measurements, and use the resulting mass of the dynamical ejecta to estimate its contribution (without the effects of wind ejecta) to the corresponding kilonova light curves from various models. The distributions of dynamical ejecta mass range between M-ej = 10(-3) - 10(-2) M-circle dot for various equations of state, assuming that the neutron stars are rotating slowly. In addition, we use our estimates of the dynamical ejecta mass and the neutron star merger rates inferred from GW170817 to constrain the contribution of events like this to the r-process element abundance in the Galaxy when ejecta mass from post-merger winds is neglected. We find that if greater than or similar to 10% of the matter dynamically ejected from binary neutron star (BNS) mergers is converted to r-process elements, GW170817-like BNS mergers could fully account for the amount of r-process material observed in the Milky Way.